URL Parameters in GSC contains strange values for recently crawled URLs

Question

I've been fighting the Google canonical page algorithm bug for quite some time. One advice I received is to set GSC URL Parameters to "Every URL", since we use a page generation script with a "page" parameter, and do not use "Let Googlebot decide". When setting that, if I click on "Show example URLs", GSC shows something like this for recently crawled URLs:

index.pl?page=nhcuofak
index.pl?page=mgiwznbsiwhmbh
index.pl?page=cbmtogqjbgakj
index.pl?page=kzktuwhan
index.pl?page=uxuatqqr
:
:

Also I've attached a screen shot: For sure none of these pages exist on our web server. As far as I can tell, our GSC account has not been hacked, at least I don't see any evidence of anyone submitting indexing requests other than me. Entering any of these parameters causes our site to return a hard 404. Why would Google be crawling with random page parameter values ? And a corollary question, could this affect Google's canonical page selection ?

Answer 1

I'm posting an answer as I think I know what's going on with the gibberish crawls. I found referring URLs for some of these crawls in our server access logs, such as (replace example with signalogic):

http://ftp.example.com/nhcuofak.html

and these were coming from backlink / spam bots (evidently Google sees these requests in the wild and decides to crawl them ?). Our htaccess was letting these through, so our page-gen script was looking up the gibberish and returning 200 along with some nice "page not found" html. I have since modified our htaccess to return 404 for anything not http(s) followed by either nothing or www. Google will now see these as 404 and hopefully stop showing them on the recently crawled list.

Note this has no effect on the Google canonical page algorithm issues, which remain ongoing (a separate post here).